Thanks for all the engagement on this. I work with designs used in industrial and commercial applications with power distribution gear. Often asynchronous serial RS485 daisy chained links are what we use to bring metering information to a central gateway. On one side is the local RS485 link which I do not think of as a telecom system and then on the other side of the gateway we typically have Ethernet which does fit.
I can see where the emission issues have a lot of meaning in telecom links since we need to keep this common/public link clean. At the same time I appreciate that my local proprietary RS485 link should strive to meet the same goal but I do want to know when I will be regulated to do so and want to see the boundaries clearly. We all need to know where the line lays and try to keep on the proper side. Another tangent on telecom is in regards to safety. To me telecom brings in exposure to surge from links outside of a building. Telecom POTS systems represent some of the more dangerous circuits that you can be exposed to. In contrast an RS485 system restricted to the inside of a building does not represent the same threat. Regards Chris Wells Eaton Electrical From: [email protected] [mailto:[email protected]] On Behalf Of Steve O'Steen Sent: Tuesday, September 15, 2009 1:38 PM To: John Woodgate; [email protected] Subject: RE: EMC question John/Ghery, >Note the distinction contained in the note. The list is not >exhaustive, but should illustrate the intent. Ports for connecting >boxes in a system are not telecom. Ports for connecting ?stuff? over a >wide distance are telecom. Would this still apply even if the boxes were connected via CAT5 cable? Would the label "Telecom Port" only be applied if both criteria were met; "wide distance" and the appropriate medium for that distance? These are issues we, as a compliance lab, face on a daily basis and our clients are relying on our expertise and true understanding of the how-to as well as the intent of a standard. Once you understand the intent, everything else falls into place, or should. I'm struggling with the whole Telecom port issue a bit because I think I understand the intent but have not been able to establish criteria as to when this test applies. Most of our customers are content to have all LAN ports tested but, knowing that some of the ports on the shelf are loop back using a 6' CAT5e to an adjacent card seems excessive. Would this fall into Ghery's example of "ports for connecting boxes in a system" even if connected via CAT5 where extended lengths could be used or was that statement specific to other types of cable? Thanks, Steve O'Steen Director, EMC Advanced Compliance Solutions, Inc. [email protected] 770-831-8048 ext. 210 www.acstestlab.com ****************CONFIDENTIAL**************** This e-mail and any attachments may contain information which is confidential, proprietary, privileged or otherwise protected by law. The information is solely intended for the named addressee (or a person responsible for delivering it to the addressee). If you are not the intended recipient of this message, you are not authorized to read, print, retain, copy or disseminate this message or any part of it. If you have received this e-mail in error, please notify the sender immediately by return e-mail and delete it from your computer. From: [email protected] [mailto:[email protected]] On Behalf Of John Woodgate Sent: Tuesday, September 15, 2009 12:52 PM To: [email protected] Subject: Re: EMC question In message <4c5e6457cd7911469a07260381288c2846285...@orsmsx502.amr.corp.intel.com>, dated Tue, 15 Sep 2009, "Pettit, Ghery" <[email protected]> writes: >Note the distinction contained in the note. The list is not >exhaustive, but should illustrate the intent. Ports for connecting >boxes in a system are not telecom. Ports for connecting ?stuff? over a >wide distance are telecom. Indeed. An additional point is that for compliance with the EMC Directive, the **manufacturer's intention** is crucial. If a user decides to extend a USB connection, for example, to 25 m, and it works well enough to allow him to use it, the manufacturer has not violated the Directive, because he did not *intend* a user to do that. In some countries, it may be legally wise to *list* the intentions, to avoid claims of 'You should have told me (the coffee would be hot)!'. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Things can always get better. But that's not the only option. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. 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Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]> - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. 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